Maximally Permissive Mutually & Globally Nonblocking Supervision with Application to Switching Control

A supervisor is said to be mutually nonblocking with respect to a pair of speci-cations if upon completing a task in any of the specications, it can continue on to complete the task in the other specication, i.e., the two specications do not block each other. The notion of mutually nonblocking supervisor was introduced in [4, 5]. In this paper we present an algorithm of polynomial complexity for computing a maximally permissive mutually and globally nonblocking supervisor. In case such a supervisor does not exist, we present a technique for relaxing the specications for which a super-visor exists. The algorithms are based on a notion of attractability, and as a special case oer a new way of computing the maximally permissive nonblocking supervisors. The results are then applied to design of maximally permissive switching supervisors so as to allow for switching between the specications at any time while the system is executing